Jig for cutting variable resistor shafts



A ril s, 1958 M. BIALER 2, 2

v JIG FOR CUTTING VARIABLE RESISTOR SHAFTS Filed Dec. 12, 1955 INVENTOR. /V/9X B//?( e the element.

The invention described herein may be manufactured and used by or for the Government for governmental purposes Without the payment to me of any royalty thereon.

This invention relates to a portable jig device which facilitates the handling of variable resistors and which eliminates the danger of damaging the resistor element due to the vibration and stress set up during the cutting off operation of the resistor shaft to a desired length.

Formerly, it has been necessary to form in a support a bore having a high degree of tolerance. For instance, to accommodate a quarter inch diameter shaft for cutting, it was necessary to obtain bearing tolerances of the order of The main drawback in the use of the bearing only to hold the shaft for cutting was that the vibration and stresses set up during the cutting were transmitted to the resistor element at the end of the shaft, oftentimes damaging Vises have also been used to hold the shaft in an attempt to alleviate the vibration and stresses on the resistor; however, this was not successful in preventing the transmission of the vibration to the fragile resistor element. In this invention, the problem is eliminated by providing means to clamp the shaft securely against the bearing surface. In this way, the clamping means applied about the shaft absorbs the vibration and stresses and the resistor element is supported thus preventing dam- 7 age to the resistor element. As a result, it is also unnec essary to provide a bearing of such high tolerance,.thus reducing the expense of manufacture of this jig.

In the past, it has also been the usual procedure to first measure and mark the desired length of shaft. This invention obviates the necessity of such practice by providing an adjustable supporting and measuring means attached to the cutting block.

With these and other advantages in view, this invention will be best understood by referring to the following description of a preferred embodiment of my invention, taken in connection with the accompanying drawings, in which:

Fig. 1 is a perspective view of the preferred form of this invention;

Fig. 2 is a front plan view of the same;

Fig. 3 is a side elevational View, the cutting block being broken away to show the shaft socket; and

Fig. 4 is a perspective View of a modified form of this invention.

Referring more particularly to the drawings, there is shown the metallic support section 1 comprising the horizontal surface 2 for clamping or bolting to a work table, and an upright portion 3 integral with the surface 2 for clamping in a vise. Integral with the section 3 or rigidly mounted on it is the elongate metal block 4 having a longitudinal bore 5 therethrough with an enlarged concentric opening 6 at its entrance for receiving the threaded bushing on shafts for shorter shaft length cuts.

' atent O F 2,29,425 Patented Apr. 8, 1958 ice Extending vertically through the block and perpendicular to the longitudinal axis of bore 5 is the cutoff guide opening 7 for guiding a saw blade in cutting the shaft. At the end of the bore is provided a shallow hori zontal slot 8 which extends across the width of the block, along the transverse horizontal axis of bore 5. Round, threaded openings 9 and 10 extend perpendicularly to one side and top of the block 4 respectively from the exterior of the. block into the bore 5 at right angles to each other. They provide threaded openings for the set screws 11 and 12 respectively.

An adjustable arcuate bed 14 is positioned upon the entrance side of the horizontal surface 2 with its sides curving upwardly and outwardly from the middle lengthwise section of the bed. Attached to the middle section of the bed 14 is the tongue 15 mounted within the key way or guide slot 13 to permit slidable up and down movement of the bed or rest 14 in relation to the slot 23 and bore 5. A vertical adjustment screw 16 is carried by the horizontal surface or extension 2 to set the bed or rest 14 at the desired vertical position on the guide for supporting the resistor element and shaft. A shaft length measurement indicator or scale 17 is provided on the side of the bed 14 to insure accurate placement of the resistor shaft for the cutting operation.

In operation, the resistor shaft (not shown) is slid into the bore 5. The desired length to be cut may be obtained by setting the end of the shaft at the corresponding measurement on the indicator, which denotes the length from that point to the cut off guide slot '7. The set screws A modified form of the invention is illustrated in Fig.

4. This particular jig is adaptable when necessary to cut a greater variety of lengths without change of adjustment. There is shown a horizontal surface 20 clamped to a Work table by means of the screws 21 and 22. The elongate block 23 is provided with three or more vertical cut-off guide slots 24, 25, and 26. As described hereinbefore, the block 23 is provided with a bore 27, the enlarged opening 28, and transverse bores 29 and 38 for placement of the screws 31 and 32 respectively intermediate the entrance side of the block 23 and cut-off guide slot 24. The modified form does not include the bed, for it has been found that each resistor may be positioned and cut more easily without readjusting the bed for each varied size.

In conclusion, there has been described a jig utilizing a simple means of clamping and supporting a resistor shaft to gain substantial advantages in the process of cutting variable resistor shafts. It is simple and inexpensive to manufacture, yet highly efiicient and accurate operation. Due to its compactness and accuracy, it has been found particularly useful in field operations, assuring little danger of damaging the resistor elements mounted on the shafts.

Obviously, many changes within the scope of the following claims may be resorted to. The above detailed description is not to be construed as limiting the invention to the precise construction described and shown.

What is claimed is:

1. A jig for cutting variable resistor shafts having a resistor element thereon to predetermined lengths comprising, supporting means, an elongate block mounted upon said supporting means, said block being provided with a bore extending lengthwise thercthrough, a transverse vertical cut off guide slot intermediate the ends of the bore and a horizontal slot opening at the outer end of said bore adaptable for receiving a cutting tool for the cutting and slotting of said shaft respectively, two set screws threadable through said blocl: into said bore to engage and reto said bore, a first set screw to extend through said block 1 and into said bore, and a second set screw to extend through said block and into said bore at right angles to said first set screw, said set screws being movable into said bore to engage and rigidly support the resistor shaft within said bore for the cutting operation.

3. A jig for cutting a shaft of variable length and diam-- eter comprising a block member having a bore passing therethrough and at least one transverse cutoil guide opening extending through said block perpendicular to said bore, first means to extend through the thickness of said block and into said here, and second means to extend through the thickness of said block and into said bore at right angles to said first means and in transverse alignment therewith, said first and second means being movable into said bore to engage the resistor shaft at spaced peripheral points between sai guide opening and the entrance to said bore and to cooperate with the wall of said bore to embrace the shaft against movement and vibration during the cutting operation. 4

4. A jig for cutting a shaft of variable length and diameter comprising a support member, an elongate block member disposed on said support member, said block having a bore passing lengthwise therethrough and at least one transverse cutoff guide opening extending through said block perpendicular to said bore, a first set screw member to extend through the thickness of said block and into said bore adjacent said guide opening, and a second set screw member to extend through the thickness of said block and into said bore at right angles to said first set screw and in transverse alignment therewith, said set screws being threadable into said bore and cooperable with the wall of said bore to engage and tightly hold the resistor shaft Within said bore against movement and vibration during the cutting operation.

References Cited in the file of this patent i V UNETED STATES PATENTS 1,577,735 Laparle Mar. 23, 1926 2,455,024 Schneider Nov. 30, 1948 2,598,117 Ethridge May 27, 1952 2,680,980 Franck June 15, 1954 2,746,125 Cuny May 22,1956 

